Defect formation caused by a transient decrease in the ambient oxygen concentration during growth of YBa2Cu3O7−δ films

Abstract

Thin films of YBa₂Cu₃O_7−δ have been grown in an oxygen atmosphere by pulsed laser deposition using two synchronized lasers, separated by a variable delay (1 μs–10 ms). The ablated fragments from the first laser lead to formation of a blast wave in O₂, leaving behind a rarefied ambient. If the second laser is triggered before the O₂ pressure returns to equilibrium, the resulting films show a decrease in transition temperature with an expanded c‐lattice parameter caused by defects in the nonchain sites of YBa₂Cu₃O_7−δ. This demonstrates the necessity of maintaining a sufficiently high concentration of oxygen within the time period that the fragments travel and deposit on the substrate.